1. Field
The present invention relates to a method and a device for detecting frame synchronization of an LTE signal, and a relay device adopting the same.
2. Description of Related Art
In order to detect frame synchronization of an LTE system, temporal positions of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) in a frame need to be found. For example, FIG. 1 illustrates positions of the PSS and the SSS in the case of an LTE system having a time division duplexing (TDD) structure. The length of one frame is 10 ms and in this case, the PSS and the SSS are transmitted in a specific frequency band with a cycle of 5 ms. Two synchronization signals are generated with a specific sequence selected among predetermined multiple candidate sequence sets.
As the related art for detecting the frame synchronization of the LTE system, provided is a technology that detects the frame synchronization through a correlation calculation with candidate sequences of the PSS and the SSS in a frequency domain by a FFT calculation. Since the LTE system uses OFDM by a modulation scheme, the LTE system fundamentally performs the FFT calculation in order to demodulate a received signal, and as a result, it is possible to naturally detect the frame synchronization by using the PSS and the SSS during the existing FFT calculation process. However, in equipment that does not demodulate a signal like a repeater system, it is inappropriate to use the corresponding technology by a burden of the FFT calculation.
Provided is the related art that detects the frame synchronization through the correlation calculation of the PSS and the SSS in a time domain in order to solve such a disadvantage. The corresponding technology extracts bands at which the PSS and the SSS are positioned from the received signal through a low pass filter and detects the frame synchronization of the extracted PSS and SSS through the correlation calculation with the candidate sequences of the PSS and the SSS which are defined in advance. Accordingly, since the corresponding technology does not require a complicated FFT calculation, the corresponding technology has a lower calculation degree than the aforementioned technology, but the correlation calculation is continuously performed in the time domain, and as a result, the calculation degree is still high. Further, when a frequency offset is existed, it is disadvantageous in that a correlation characteristic deteriorates.